Touch detector and method of driving the same, display with touch detection function, and electronic unit having plural different drive electrodes

ABSTRACT

A touch detector capable of achieving high position resolution while improving detection sensitivity to a touch is provided. The touch detector includes: a plurality of drive electrodes arranged side by side to extend in one direction; a detection electrode extending in a direction orthogonal to a direction where the drive electrodes extend, and arranged to form a capacitance at each of intersections with the drive electrodes; and a scanning drive section sequentially selecting a predetermined plural number of target electrodes from the plurality of drive electrodes in a time-divisional manner, and applying a touch detection drive signal with a plurality of pulse waveforms for detecting an external adjacent object to the selected target electrodes to perform a scanning drive. A scanning pitch in the scanning drive is smaller than the total width of the plural number of selected target electrodes.

CROSS REFERENCES TO RELATED APPLICATIONS

The present invention is a Continuation of application Ser. No.14/678,422, filed on Apr. 3, 2015, which is a Continuation ofapplication Ser. No. 13/137,340, filed on Aug. 8, 2011, now U.S. Pat.No. 9,035,900, issued on May 19, 2015, which claims priority to JapanesePatent Application Number 2010-214188, filed on Sep. 24, 2010, theentire contents of which are incorporated herein by reference.

BACKGROUND

The present technology relates to a touch detector, and morespecifically relates to a touch detector detecting a touch based on achange in capacitance by an external adjacent object and a method ofdriving the same, a display with a touch detection function and anelectronic unit including such a touch detector.

In recent years, attention has been given to a display capable ofinputting information by a button image instead of a typical mechanicalbutton by being provided with a contact detection device, that is, aso-called touch panel mounted on or integrated with a display such as aliquid crystal display and displaying various button images on thedisplay. As a display including such a touch panel does not need aninput device such as a keyboard, a mouse or a keypad, there is atendency to expand the use of such a display to portable informationterminals such as cellular phones in addition to computers.

Systems of touch detectors include an optical system, a resistancesystem and the like, but expectations are placed on a capacitance systemtouch detector which has a relatively simple configuration and isallowed to achieve low power consumption. For example, JapaneseUnexamined Patent Application Publication No. 2009-244958 proposes adisplay in which a common electrode for display originally included in adisplay also serves as one (a drive electrode) of a pair of electrodesfor touch sensor and the other (a touch detection electrode) is arrangedto intersect the common electrode. A capacitance is formed between thedrive electrode and the touch detection electrode, and the capacitanceis changed by an external adjacent object. This display analyzes a touchdetection signal obtained from the touch detection electrode when adrive signal is applied to the drive electrode to detect the externaladjacent object with use of the change in the capacitance. In thisdisplay, while the drive signal is sequentially applied to the commonelectrode (drive electrode) to perform line-sequential scanning, therebyperforming a display operation, the touch detection signal obtained fromthe touch detection electrode in response to the drive signal isanalyzed to perform a touch detection operation.

SUMMARY

Important characteristics of a touch detector include detectionsensitivity to a touch and position resolution for touch positiondetection. To improve detection sensitivity in a capacitance systemtouch detector, for example, a method of increasing the width of a driveelectrode is considered. However, in this case, a scanning pitch intouch detection scanning is increased to cause rough scanning, andposition resolution may be deteriorated accordingly.

It is desirable to provide a touch detector achieving high positionresolution while improving detection sensitivity to a touch, and amethod of driving the same, a display with a touch detection function,and an electronic unit.

According to an embodiment of the technology, there is provided a touchdetector including: a plurality of drive electrodes, a detectionelectrode; and a scanning drive section. The plurality of driveelectrodes are arranged side by side to extend in one direction. Thedetection electrode extends in a direction orthogonal to a directionwhere the drive electrodes extend, and is arranged to form a capacitanceat each of intersections with the drive electrodes, The scanning drivesection sequentially selects a predetermined plural number of targetelectrodes from the plurality of drive electrodes in a time-divisionalmanner, and applies a touch detection drive signal with a plurality ofpulse waveforms for detecting an external adjacent object to theselected target electrodes to perform a scanning drive. A scanning pitchin the scanning drive is smaller than the total width of the pluralnumber of selected target electrodes.

According to an embodiment of the technology, there is provided a methodof driving a touch detector including: sequentially selecting apredetermined plural number of target electrodes from a plurality ofdrive electrodes, which is arranged side by side to extend in onedirection, in a time-divisional manner, and applying a touch detectiondrive signal with a plurality of pulse waveforms for detecting anexternal adjacent object to the selected target electrodes to perform ascanning drive with a scanning pitch, the scanning pitch being smallerthan the total width of the plural number of selected target electrodes;and detecting the external adjacent object based on a detection signalof a detection electrode which extends in a direction orthogonal to adirection where the drive electrodes extend and is arranged to form acapacitance at each of intersections with the drive electrodes.

According to an embodiment of the technology, there is provided adisplay with a touch detection function including: a plurality of driveelectrodes, a detection electrode, a display element; and a scanningdrive section. The plurality of drive electrodes are arranged side byside to extend in one direction. The detection electrode extends in adirection orthogonal to a direction where the drive electrodes extendand is arranged to form a capacitance at each of intersections with thedrive electrodes. The display element performs display based on a pixelsignal and a display drive signal. The scanning drive section performs afirst scanning drive sequentially applying the display drive signal tothe plurality of drive electrodes in a time-divisional manner, and asecond scanning drive sequentially selecting a predetermined pluralnumber of target electrodes from the plurality of drive electrodes in atime-divisional manner and applying a touch detection drive signal witha plurality of pulse waveforms for detecting an external adjacent objectto the selected target electrodes. A scanning pitch in the secondscanning drive is smaller than the total width of the plural number ofselected target electrodes.

According to an embodiment of the technology, there is provided anelectronic unit including the above-described touch detector, andcorresponds to, for example, a television, a digital camera, a personalcomputer, a video camera or a portable terminal device such as acellular phone.

In the touch detector, the method of driving a touch detector, thedisplay with a touch detection function and the electronic unitaccording to the embodiment of the technology, the touch detection drivesignal with a plurality of pulse waveforms is applied to thepredetermined plural number of target electrodes sequentially selectedin a time-divisional manner to perform a scanning drive for touchdetection. The scanning drive is performed with a scanning pitch smallerthan the total width of the plural number of selected target electrodes.

For example, the touch detector according to the embodiment of thetechnology preferably further includes a touch detection sectionsampling a detection signal of the detection electrode at timingsaccording to transitions of the plurality of pulse waveforms of thedrive signal to detect an external adjacent object. In this case, everytime the scanning drive section drives the target electrodes, the touchdetection section preferably completes detection of an external adjacentobject in a region corresponding to the driven target electrodes, andthe touch detection section preferably determines a touched positionbased on all detection results obtained from the target electrodessequentially selected.

The drive electrodes are allowed to be configured by, for example, thefollowing two methods.

For example, the plurality of drive electrodes may have equal widths. Inthis case, in the scanning drive, while the touch detection drive signalis simultaneously applied to the predetermined plural number of targetelectrodes, scanning is allowed to be performed to shift targetelectrodes by a number smaller than the predetermined plural number at atime.

Moreover, for example, the plurality of drive electrodes may include twokinds of drive electrodes with different widths, and the two kinds ofdrive electrodes may be alternately arranged side by side. In this case,in the scanning drive, while the touch detection drive signal issimultaneously applied to three adjacent target electrodes selected fromthe two kinds of drive electrodes which are alternately arranged side byside, scanning is allowed to be performed to shift target electrodes bytwo electrodes at a time.

In the touch detector and the method of driving a touch detector, thedisplay with a touch detection function and the electronic unitaccording to the embodiment of the technology, the scanning pitch issmaller than the total width of the plural number of target electrodes;therefore, while improving detection sensitivity to a touch, highposition resolution is achievable.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, and are intended toprovide further explanation of the technology as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the disclosure, and are incorporated in and constitutea part of this specification. The drawings illustrate embodiments and,together with the specification, serve to explain the principles of thetechnology.

FIG. 1 is an illustration for describing a basic principle of a touchdetection system in a touch detector according to an embodiment of thetechnology in a state where a finger does not touch or does not comeclose to the touch detector.

FIG. 2 is an illustration for describing the basic principle of thetouch detection system in the touch detector according to the embodimentof the technology in a state where a finger touches or comes close tothe touch detector.

FIG. 3 is an illustration of an example of waveforms of a drive signaland a touch detection signal for describing the basic principle of thetouch detection system in the touch detector according to the embodimentof the technology.

FIG. 4 is a block diagram illustrating a configuration example of atouch detector according to a first embodiment of the technology.

FIG. 5 is a perspective view illustrating configuration examples ofdrive electrodes and a touch detection electrode in a touch detectiondevice illustrated in FIG. 4.

FIG. 6 is a schematic view illustrating an operation example of ascanning drive of the touch detector illustrated in FIG. 4.

FIG. 7 is a timing waveform chart illustrating an operation example ofthe touch detector illustrated in FIG. 4.

FIG. 8 is a schematic view illustrating an operation example of ascanning drive of the touch detector illustrated in FIG. 4.

FIGS. 9A and 9B are schematic views illustrating operation examples ofscanning drives of touch detectors according to comparative examples.

FIG. 10 is a plan view illustrating a configuration example of driveelectrodes in a touch detection device according to a second embodiment.

FIG. 11 is a block diagram illustrating a configuration example of adisplay with a touch detection function according to a third embodiment.

FIG. 12 is a schematic sectional view illustrating a configuration of adisplay device with a touch detection function illustrated in FIG. 11.

FIG. 13 is a circuit diagram illustrating a pixel arrangement of thedisplay device with a touch detection function illustrated in FIG. 11.

FIG. 14 is an external perspective view of Application Example 1 of thetouch detector according to any of the embodiments.

FIGS. 15A and 15B are external perspective views of Application Example2.

FIG. 16 is an external perspective view of Application Example 3.

FIG. 17 is an external perspective view of Application Example 4.

FIGS. 18A to 18G are front, side, top and bottom views of ApplicationExample 5.

FIG. 19 is a schematic sectional view illustrating a configuration of adisplay device with a touch detection function according to amodification.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the technology will be described in detailbelow referring to the accompanying drawings. Descriptions will be givenin the following order.

1. Basic principle of capacitance system touch detection

2. First Embodiment (Touch detector)

3. Second Embodiment (Touch detector)

4. Third Embodiment (Display with touch detection function)

5. Application Examples

1. Basic Principle of Capacitance System Touch Detection

First, referring to FIG. 1 to FIG. 3, a basic principle of touchdetection by a touch detector according to an embodiment of thetechnology will be described below. This touch detection is embodied bya capacitance system touch sensor, and for example, as illustrated in apart A in FIG. 1, a capacitive element is configured of a pair ofelectrodes (a drive electrode E1 and a touch detection electrode E2)arranged to face each other with a dielectric D in between. Such aconfiguration is illustrated as an equivalent circuit illustrated in apart B in FIG. 1. A capacitive element C1 is configured of the driveelectrode E1, the touch detection electrode E2 and the dielectric D. Inthe capacitive element C1, one end thereof is connected to an AC signalsource (a drive signal source) S, and the other end P thereof isgrounded through a resistor R and is connected to a voltage detector (atouch detection circuit) DET. When an AC rectangular wave Sg (refer to apart B in FIG. 3) with a predetermined frequency (for example,approximately a few kHz to ten-odd KHz) is applied from the AC signalsource S to the drive electrode E1 (the one end of the capacitiveelement C1), an output waveform (a touch detection signal Vdet) asillustrated in a part A in FIG. 3 appears in the touch detectionelectrode E2 (the other end P of the capacitive element C1). Inaddition, the AC rectangular wave Sg corresponds to a touch detectiondrive signal Vcomt which will be described later.

In a state where a finger does not touch (or come close to) the touchdetection electrode E2, as illustrated in FIG. 1, a current I₀ accordingto the capacitance value of the capacitive element C1 flows duringcharging and discharging the capacitive element C1. A potential waveformat the other end P of the capacitive element C1 at this time is, forexample, as illustrated by a waveform V₀ in the part A in FIG. 3, andthe waveform V₀ is detected by the voltage detector DET.

On the other hand, in a state where the finger touches (or comes closeto) the touch detection electrode E2, as illustrated in FIG. 2, acapacitive element C2 formed by the finger is added to the capacitiveelement C1 in series. In this state, currents I₁ and I₂ flow duringcharging and discharging the capacitive elements C1 and C2,respectively. The potential waveform at the other end P of thecapacitive element C1 at this time is, for example, as illustrated by awaveform V₁ in the part A in FIG. 3, and the waveform V₁ is detected bythe voltage detector DET. At this time, the potential at a point P is adivided potential determined by the values of the current I₁ and I₂flowing through the capacitive elements C1 and C2, respectively.Therefore, the waveform V₁ has a smaller value than that of the waveformV₀ in a non-touch state. The voltage detector DET compares a detectedvoltage with a predetermined threshold voltage V_(th), and when thedetected voltage is equal to or higher than the threshold voltageV_(th), the voltage detector DET determines that the state is in anon-touch state, and when the detected voltage is smaller than thethreshold voltage V_(th), the voltage detector DET determines that thestate is a touch state. Thus, touch detection is allowed in such amanner.

2. First Embodiment Configuration Example Whole Configuration Example

FIG. 4 illustrates a configuration example of a touch detector 1according to a first embodiment of the technology. The touch detector 1is of a capacitance system using a change, caused by an externaladjacent object, in capacitance between electrodes intersecting eachother. It is to be noted that a method of driving a touch detectoraccording to an embodiment of the technology is embodied by theembodiment and will be also described below.

The touch detector 1 includes a control section 11, a drive electrodedriver 14, a touch detection device 30 and a touch detection section 40.

The control section 11 is a circuit supplying control signals to thedrive electrode driver 14 and the touch detection section 40,respectively, and controlling the drive electrode driver 14 and thetouch detection section 40 to operate in synchronization with eachother.

The drive electrode driver 14 is a circuit supplying a touch detectiondrive signal Vcomt to a drive electrode COML (which will be describedlater) of the touch detection device 30 in response to the controlsignal supplied from the control section 11. The touch detection drivesignal Vcomt is a signal with a plurality of pulse waveforms. As will bedescribed later, the drive electrode driver 14 simultaneously appliesthe touch detection drive signal Vcomt to a predetermined number ofdrive electrodes COML and performs scanning on drive electrodes COML toshift drive electrodes COML by a number smaller than the predeterminednumber of drive electrodes COML to which the touch detection drivesignal Vcomt is simultaneously applied.

The touch detection device 30 operates based on a basic principle of theabove-described capacitance system touch detection to output a touchdetection signal Vdet. As will be described later, the touch detectiondevice 30 performs scanning in response to the touch detection drivesignal Vcomt supplied from the drive electrode driver 14 to performtouch detection.

FIG. 5 illustrates a perspective view of a configuration example of thetouch detection device 30. The touch detection device 30 is configuredof the drive electrodes COML and a touch detection electrode TDL. Thedrive electrodes COML extend in a lateral direction in the drawing, andare formed with equal widths and arranged side by side. When the touchdetection operation is performed, the touch detection drive signal Vcomtis sequentially supplied to electrode patterns of the drive electrodesCOML by the drive electrode driver 14 to perform a sequential-scanningdrive in a time-divisional manner. The touch detection electrode TDL isconfigured of electrode patterns extending in a direction orthogonal toa direction where electrode patterns of the drive electrodes COMLextend. The electrode patterns of the touch detection electrode TDL areconnected to the touch detection section 40. A capacitance is formed ateach of intersections of the electrode patterns of the drive electrodesCOML and the electrode patterns of the touch detection electrode TDL.

In this configuration, in the touch detection device 30, the driveelectrode driver 14 applies the touch detection drive signal Vcomt tothe drive electrodes COML to output the touch detection signal Vdet fromthe touch detection electrode TDL, thereby performing touch detection.In other words, the drive electrode COML corresponds to the driveelectrode E1 in the basic principle of touch detection illustrated inFIGS. 1 to 3, and the touch detection electrode TDL corresponds to thetouch detection electrode E2, and the touch detection device 30 detectsa touch based on the basic principle. As illustrated in FIG. 5,electrode patterns intersecting each other configure capacitance systemtouch sensors in a matrix form. Therefore, scanning is performed over anentire touch detection surface of the touch detection device 30 to allowdetection of a position where an external adjacent object touches orcomes close.

The touch detection section 40 is a circuit which detects the presenceor absence of a touch based on a control signal supplied from thecontrol section 11 and a touch detection signal Vdet supplied from thetouch detection device 30 and determines coordinates or the like of atouch in a touch detection region in the case where the presence of atouch is detected. The touch detection section 40 includes an analog LPF(Low Pass Filter) section 42, an A/D conversion section 43, a signalprocessing section 44, a coordinate extraction section 45 and adetection timing control section 46. The analog LPF section 42 is ananalog low pass filter removing a high frequency component (a noisecomponent) included in the touch detection signal Vdet supplied from thetouch detection device 30 to obtain and output a touch component. Aresistor R for supplying a DC potential (0 V) is connected between eachinput terminal of the analog LPF section 42 and a ground. It is to benoted that instead of the resistor R, for example, a switch may bearranged, and the switch may be turned on at a predetermined time tosupply the DC potential (0 V). The A/D conversion section 43 is acircuit sampling an analog signal supplied from the analog LPF section42 at a timing in synchronization with the touch detection drive signalVcomt to convert the analog signal into a digital signal. The signalprocessing section 44 is a logic circuit detecting the presence orabsence of a touch based on an output signal from the A/D conversionsection 43. The coordinate extraction section 45 is a logic circuitdetermining a touched position by an interpolation operation when atouch is detected in the signal processing section 44. The detectiontiming control section 46 controls these circuits to operate insynchronization with one another.

The touch detection electrode TDL corresponds to a specific example of“a detection electrode” in the technology. The drive electrode driver 14corresponds to a specific example of “a scanning drive section” in thetechnology.

[Operation and Functions]

Next, the operation and functions of the touch detector 1 according tothe embodiment will be described below.

(Summary of Entire Operation)

First, referring to FIG. 4, a summary of an entire operation of thetouch detector 1 will be described below. The control section 11supplies control signals to the drive electrode driver 14 and the touchdetection section 40, respectively, thereby controlling the driveelectrode driver 14 and the touch detection section 40 to operate insynchronization with each other. The drive electrode driver 14sequentially applies the touch detection drive signal Vcomt with aplurality of pulse waveforms to the drive electrodes COML of the touchdetection device 30. The touch detection device 30 performs a touchdetection operation in response to the touch detection drive signalVcomt to output the touch detection signal Vdet from the touch detectionelectrode TDL. The analog LPF section 42 removes a high frequencycomponent of the touch detection signal Vdet to output the resultantsignal Vdet. The A/D conversion section 43 converts an analog signalsupplied from the analog LPF section 42 into a digital signal at atiming in synchronization with the touch detection drive signal Vcomt.The signal processing section 44 detects the presence or absence of atouch based on an output signal from the A/D conversion section 43. Thecoordinate extraction section 45 determines a touched position when atouch is detected in the signal processing section 44. The detectiontiming control section 46 controls the analog LPF section 42, the A/Dconversion section 43, the signal processing section 44 and thecoordinate extraction section 45 to operate in synchronization with oneanother.

(Specific Operation)

Next, a scanning drive operation will be described in detail below.

FIG. 6 illustrates an operation example of a scanning drive of the touchdetector 1. As illustrated in FIG. 6, the drive electrodes COML areformed with equal widths and arranged side by side. The drive electrodedriver 14 drives a predetermined number of drive electrodes COML (forexample, a drive area A1) in synchronization with one another. The touchdetection device 30 transmits the touch detection drive signal Vcomtapplied to each of the predetermined number of drive electrodes COML tothe touch detection electrode TDL through a capacitance, and outputs thetouch detection drive signal Vcomt as a touch detection signal Vdet. Inother words, a region including the predetermined number of driveelectrodes COML (for example, the drive area A1) becomes a touchdetection region at that time in a touch detection surface, and thewidth (a touch detection width b) of the region is equal to the totalwidth of the predetermined number of drive electrodes COML. Then, thedrive electrode driver 14 performs a scanning drive on the driveelectrodes COML in order of drive areas A1, A2, A3, A4, . . . in atime-divisional manner. In other words, the drive electrode driver 14performs a scanning drive with a scanning pitch a. In this example, thedrive electrode driver 14 simultaneously drives five drive electrodesCOML (the touch detection width b) while scanning the drive electrodesCOML to shift drive electrodes COML by four drive electrodes COML (thescanning pitch a).

In the touch detector 1, the scanning pitch a and the touch detectionwidth b are allowed to be set freely depending on a way of driving thedrive electrodes. More specifically, the scanning pitch a is allowed tobe set by the number of drive electrodes in a section where adjacentdrive areas (for example, the drive area A1 and the drive area A2)overlap each other in FIG. 6. Moreover, the touch detection width b isallowed to be set by the number of drive electrodes in each drive areaAn (where n is a natural number). Thus, in the touch detector 1, thescanning pitch a and the touch detection width b are allowed to be setindependently.

The scanning pitch a correlates with position resolution when a touchedposition is detected. More specifically, typically, a reduction in thescanning pitch a allows the position resolution to be increased. On theother hand, the touch detection width b correlates with detectionsensitivity to a touch. Typically, an increase in the touch detectionwidth b allows the detection sensitivity to be increased, because whenthe touch detection width b is increased, the number of lines ofelectric force from the drive electrodes COML corresponding to the touchdetection width b is increased according to an area thereof.

In the touch detector 1, as the scanning pitch a and the touch detectionwidth b are allowed to be set independently, position resolution anddetection sensitivity are allowed to be set independently. For example,to increase position resolution while maintaining detection sensitivity,the scanning pitch a may be reduced while maintaining the touchdetection width b. On the other hand, to increase detection sensitivitywhile maintaining position resolution, the touch detection width b maybe increased while maintaining the scanning pitch a. Moreover, forexample, to increase both of position resolution and detectionsensitivity, the touch detection width b may be increased and thescanning pitch a may be reduced.

Thus, in the touch detector 1, as the scanning pitch a and the touchdetection width b are allowed to be set independently, positionresolution when a touched position is detected and detection sensitivityto a touch are allowed to be set independently.

FIG. 7 illustrates a timing waveform example of the touch detector 1, apart A indicates a waveform of the touch detection drive signal Vcomt,and a part B indicates a waveform of the touch detection signal Vdet.

The drive electrode driver 14 applies the touch detection drive signalVcomt with a plurality of pulse waveforms to the drive electrodes COMLfrom one of the drive area An to another in a time-divisional manner(refer to the part A in FIG. 7). The touch detection device 30 outputs asignal based on the touch detection drive signal Vcomt as the touchdetection signal Vdet (refer to the part B in FIG. 7). Then, the touchdetection section 40 separately analyzes the touch detection signalsVdet of the drive areas An to detect the presence or absence of a touch,a touched position or the like.

More specifically, first, in a period P1, the drive electrode driver 14applies the touch detection drive signal Vcomt with a plurality of pulsewaveforms to the drive electrodes COML assigned to the drive area A1(Vcomt (A1) in the part A in FIG. 7). In the touch detection device 30,the touch detection drivel signal Vcomt is transmitted to the touchdetection electrode TDL through a capacitance between the driveelectrodes COML assigned to the drive area A1 and the touch detectionelectrode TDL to change the touch detection signal Vdet (refer to thepart B in FIG. 7). The A/D conversion section 43 of the touch detectionsection 40 samples an output signal of the analog LPF section 42 towhich the touch detection signal Vdet is supplied at sampling timings isaccording to transitions of a plurality of pulse waveforms of the touchdetection drive signal Vcomt (refer to the part B in FIG. 7) to performA/D conversion. The signal processing section 44 determines the presenceor absence of a touch in a region corresponding to the drive area A1based on a plurality of A/D conversion results.

In a period P2 and subsequent periods, the touch detector 1 performstouch detection as in the case of the period P1. More specifically, forexample, in the period P2, the drive electrode driver 14 applies thetouch detection drive signal Vcomt to the drive electrodes COML assignedto the drive area A2 (Vcomt (A2) in the part A in FIG. 7). In the touchdetection device 30, the touch detection drive signal Vcomt istransmitted to the touch detection electrode TDL through a capacitancebetween the drive electrodes COML assigned to the drive area A2 and thetouch detection electrode TDL to change the touch detection signal Vdet(refer to the part B in FIG. 7). Then, the A/D conversion section 43 andthe signal processing section 44 determine the presence or absence of atouch in a region corresponding to the drive area A2 based on the touchdetection signal Vdet.

Thus, the signal processing section 44 determines the presence orabsence of a touch from one of regions corresponding to the drive areasAn to another by performing the above-described operation on an entiretouch detection surface. Then, the coordinate extraction section 45 ofthe touch detection section 40 performs an interpolation operation by,for example, an weighted average of a plurality of regions (positions)where a touch is detected based on touch detection results in all driveareas An to detect the touched position.

In the touch detector 1, the drive electrode driver 14 applies the touchdetection drive signal Vcomt with a plurality of pulse waveforms to thedrive electrodes COML from one of the drive areas An to another, and theanalog LPF section 42, the A/D conversion section 43 and the signalprocessing section 44 of the touch detection section 40 detect a touchin regions corresponding to the drive areas An based on the touchdetection signals Vdet supplied from the touch detection electrode TDL.In other words, these circuit blocks detect a touch in a regioncorresponding to each drive area An based on a plurality of samplingresults. Therefore, the sampling results are allowed to be analyzedstatistically, and a reduction in S/N ratio caused by variations insampling results is allowed to be minimized.

Moreover, in the touch detector 1, the drive electrode driver 14 appliesthe touch detection drive signal Vcomt with a plurality of pulsewaveforms to the drive electrodes COML from one of regions correspondingto the drive areas An to another, and the analog LPF section 42, the A/Dconversion section 43 and the signal processing section 44 of the touchdetection section 40 detect a touch from one of the regions to another.Therefore, it is only necessary to simply add up (average) data detectedby a plurality of drives on each of the drive regions An, therebyallowing the configuration of the touch detection section 40 to besimplified.

As a method of detecting a touch based on a plurality of samplingresults to improve an S/N ratio, in addition to the above-describedmethod, for example, a method of simultaneously applying a touchdetection drive signal with one pulse waveform to a predetermined numberof drive electrodes COML and scanning the drive electrodes COML from oneto another is considered. In such a method, in the case where detectiondata are added up (averaged) simply in the above-described manner, dataof adjacent drive electrodes COML are mixed; therefore, a considerabledecline in position accuracy may be caused. To reduce the decline inposition accuracy, for example, a method of collecting all A/Dconversion results on the entire touch detection surface and separatingcontributions by regions corresponding to respective drive electrodesCOML to determine touch detection in respective regions is considered;however, in this case, the configuration of the signal processingsection may be complicated. On the other hand, in the touch detector 1according to the embodiment, touch detection is allowed to beindependently performed from one of the drive areas An to another;therefore, the configuration of the signal processing section 44 isallowed to be simplified.

FIG. 8 illustrates an operation example of the touch detector 1. In thisexample, a finger or the like of a user touches a region (a touch regionF) across the drive areas A1 and A2. When touch detection is performedon the drive area A1, only a half of the touch region F overlaps thedrive area A1; therefore, the detection sensitivity to the touch isreduced, and it is difficult to perform touch detection. However, whenthe touch detection is performed on the drive area A2, a larger area ofthe touch detection region F overlaps the drive area A2; therefore, thedetection sensitivity is increased, and the touch detection is easilyperformed.

Thus, in the touch detector 1, when the drive electrodes COML aredriven, the drive areas An overlap one another; therefore, for example,even in the case where a region across two drive areas is touched, anarea where the touched region and the drive area An overlap each otheris allowed to be increased, thereby allowing detection sensitivity to beincreased. In other words, in the case where a drive is performed on thedrive areas An which do not overlap one another, more specifically, forexample, in the case where a drive is performed on the drive area A1 andthe drive area A2 adjacent to each other, when an area where the touchedregion and the drive area A1 overlap each other is equal to a half ofthe touched region, an area where the touched region and the drive areaA2 overlap each other is equal to a half of the touched region.Therefore, in such a case, in both of the case where touch detection isperformed on the drive area A1 and the case where touch detection isperformed on the drive area A2, detection sensitivity is reduced. On theother hand, in the touch detector 1, as illustrated in FIG. 8, when anarea where the touched region F and the drive area A1 overlap each otheris equal to a half of the touch region F, an area where the touchedregion F and the drive area A2 overlap each other is larger than a halfof the touched region F; therefore, detection sensitivity is allowed beincreased, and touch detection is allowed to be easily performed.

Comparative Examples

Next, compared to some comparative examples, functions of the embodimentwill be described below.

FIGS. 9A and 9B illustrate operation examples of scanning drives oftouch detectors according to Comparative Examples 1 and 2, respectively.In these comparative examples, as illustrated in FIGS. 9A and 9B, toincrease touch detection sensitivity, drive electrodes COMLRA and COMLRBare formed to have a larger width than that of the drive electrode COML(refer to FIG. 6) according to the embodiment.

In Comparative Examples 1 and 2, a drive electrode driver sequentiallyapplies a touch detection drive signal Vcomt with a plurality of pulsesignals to respective drive areas RAn or RBn (where n is a naturalnumber) in a time-divisional manner. In this case, the scanning pitch aand the touch detection width b are equal to the width of the drive areaRAn or RBn (in other words, the width of the drive electrode COMLRA orCOMLRB). In other words, in Comparative Examples 1 and 2, the scanningpitch a and the touch detection width b become equal to each other,thereby not allowing the scanning pitch a and the touch detection widthb to be set independently. Therefore, for example, in the case wheredetection sensitivity to a touch is not sufficient in ComparativeExample 1 illustrated in FIG. 9A, as illustrated in FIG. 9B, when thedrive electrode COMLRB with a larger width is formed (the touchdetection width b is increased) to increase detection sensitivity, thescanning pitch a is also increased to cause a reduction in positionresolution when a touched position is detected. Moreover, for example,in the case where position resolution when a touched position isdetected is not sufficient in Comparative Example 2 illustrated in FIG.9B, as illustrated in FIG. 9A, when the drive electrode COMLRA with asmaller width is formed (the scanning pitch a is reduced) to increaseposition resolution, the touch detection width b is also reduced tocause a reduction in detection sensitivity.

On the other hand, in the touch detector 1 according to the embodiment,the scanning pitch a and the touch detection width b are allowed to beset independently; therefore, position resolution when a touchedposition is detected and detection sensitivity to a touch are allowed tobe set independently. In other words, when the touch detection width bis increased and the scanning pitch a is reduced, position resolutionand detection sensitivity are allowed to be increased. In particular, inthe case where the scanning pitch a is set to be smaller than the touchdetection width b, compared to Comparative Examples 1 and 2, bothcharacteristics are allowed to be increased.

Effects

As described above, in the embodiment, as the scanning pitch a issmaller than the touch detection width b, both of position resolutionwhen a touched position is detected and detection sensitivity to a touchare allowed to be increased.

Moreover, in the embodiment, the scanning pitch a and the touchdetection width b are set by a way of driving the drive electrodes;therefore, the scanning pitch a and the touch detection width b areallowed to be set independently, and position resolution and detectionsensitivity are allowed to be set independently.

Further, in the embodiment, the drive electrode driver applies the touchdetection drive signal from one of regions corresponding to the driveareas to another, and the touch detection section detects a touch;therefore, touch detection in each of the regions corresponding to thedrive areas is allowed to be performed independently of other regions,and the configuration of the touch detection section is allowed to besimplified.

Moreover, in the embodiment, as the drive areas overlap one another, forexample, in the case where a region across two drive areas is touched,an area where the touched region and the drive area overlap each otheris allowed to be increased, thereby increasing detection sensitivity.

3. Second Embodiment

Next, a touch detector 5 according to a second embodiment of thetechnology will be described below. In the first embodiment (refer toFIG. 6), the touch detection device 30 is configured with use of driveelectrodes COML with equal widths; however, in the embodiment, a touchdetection device 50 is configured with use of plural kinds of driveelectrodes with different widths instead of the drive electrodes withequal widths. In other words, the touch detector 5 is configured of sucha touch detection device 50 and a drive electrode driver 16 driving thetouch detection device 50. Other configurations are the same as those inthe first embodiment (refer to FIG. 4). It is to be noted that likecomponents are denoted by like numerals as of the touch detector 1according to the first embodiment and will not be further described.

FIG. 10 illustrates a configuration example of drive electrodes of thetouch detection device 50. As illustrated in FIG. 10, the touchdetection device 50 includes three kinds of drive electrodes COMLA,COMLB and COMLC with different widths. In this example, the width of thedrive electrode COMLA is substantially equal to the total width of thedrive electrode COMLB and the drive electrode COMLC. The drive electrodedriver 16 drives the drive electrodes COMLA, COMLB and COMLC incombination from one of drive areas Bn (where n is an integer) toanother. For example, the drive electrode driver 16 simultaneouslydrives the drive electrode COMLC and the drive electrodes COMLB on bothsides thereof in a drive on the drive area B2. Then, the drive electrodedriver 16 performs a scanning drive on these drive electrodes in orderof the drive areas B1, B2, B3, B4, . . . in a time-divisional manner. Atthis time, the drive electrode COMLB in a region where adjacent driveareas Bn (for example, the drive areas B2 and B3) overlap each other isused in drives on these adjacent drive areas. Thus, the drive electrodedriver 16 simultaneously drives the drive electrodes corresponding tothe touch detection width b, and performs scanning on drive electrodeswith the scanning pitch a.

As illustrated in FIG. 10, the scanning pitch a corresponds to the totalwidth of the drive electrode COMLB and the drive electrode COMLC.Moreover, the touch detection width b corresponds to the total width oftwo drive electrodes COMLB and the drive electrode COMLC. Therefore, thewidths of the drive electrodes COMLB and COMLC are allowed to bedetermined based on necessary position resolution (scanning pitch a) andnecessary detection sensitivity (touch detection width b).

In the touch detector 5, three kinds of drive electrodes COMLA, COMLBand COMLC with different widths are used. More specifically, these driveelectrodes COMLA, COMLB and COMLC (refer to FIG. 10) are configured byconnecting the drive electrodes COML simultaneously driven in the firstembodiment (refer to FIG. 6) to have a large width. Therefore, in thetouch detector 5, compared to the touch detector 1 according to thefirst embodiment, the number of drive electrodes is allowed to bereduced. Therefore, the number of drive electrodes driven by the driveelectrode driver 16 is reduced, thereby allowing the configuration ofthe drive electrode driver 16 to be simplified.

Thus, in the embodiment, plural kinds of drive electrodes with differentwidths are used; therefore, the number of drive electrodes are allowedto be reduced, and the configuration of the drive electrode driver 16 isallowed to be simplified. Other effects are the same as those in thefirst embodiment.

4. Third Embodiment

Next, a display 7 with a touch detection function according to a thirdembodiment of the technology will be described below. The display 7 witha touch detection function is a so-called in-cell type apparatusconfigured by integrating the touch detection device 30 according to thefirst embodiment and a liquid crystal display device using a liquidcrystal display element as a display element. It is to be noted thatlike components are denoted by like numerals as of the touch detector 1according to the first embodiment and will not be further described.

FIG. 11 illustrates a configuration example of the display 7 with atouch detection function. The display 7 with a touch detection functionincludes a display device 10 with a touch detection function, a controlsection 17, a gate driver 12, a source driver 13 and a drive electrodedriver 14B.

The display device 10 with a touch detection function is a displaydevice having a touch detection function. The display device 10 with atouch detection function includes a liquid crystal display device 20 anda touch detection device 30B. As will be described later, the liquidcrystal display device 20 is a device performing display whilesequentially scanning from one horizontal line to another in response toa scanning signal Vscan supplied from the gate driver 12. The touchdetection device 30B has the same configuration as that of the touchdetection device 30 according to the first embodiment.

FIG. 12 illustrates an example of a sectional configuration of a mainpart of the display device 10 with a touch detection function. Thedisplay device 10 with a touch detection function includes a pixelsubstrate 2, an opposed substrate 3 facing the pixel substrate 2 and aliquid crystal layer 6 sandwiched between the pixel substrate 2 and theopposed substrate 3.

The pixel substrate 2 includes a TFT substrate 21 as a circuit substrateand a plurality of pixel electrodes 22 arranged in a matrix form on theTFT substrate 21. Although not illustrated herein, in the TFT substrate21, thin film transistors (TFTs) of respective pixels, wiring lines suchas a pixel signal line SGL supplying a pixel signal Vpix to each pixelelectrode 22 and a scanning signal line GCL driving each TFT are formed.

The opposed substrate 3 includes a glass substrate 31, a color filter 32formed on one surface of the glass substrate 31 and a plurality of driveelectrodes COML formed on the color filter 32. The color filter 32 isconfigured by periodically arranging color filter layers of threecolors, for example, red (R), green (G) and blue (B), and a combinationof three colors R, G and B is assigned to each display pixel. Each ofthe drive electrodes COML functions as a common drive electrode of theliquid crystal display device 20, and functions as a drive electrode ofthe touch detection device 30B. The drive electrodes COML are connectedto the TFT substrate 21 through a contact conductive pillar (notillustrated), and a drive signal Vcom (a display drive signal Vcomd anda touch detection drive signal Vcomt) with an AC rectangular waveform isapplied from the TFT substrate 21 to the drive electrodes COML throughthe contact conductive pillar. A touch detection electrode TDL as adetection electrode of the touch detection device 30B is formed on theother surface of the glass substrate 31. The touch detection electrodeTDL is made of, for example, ITO (Indium Tin Oxide), and is atranslucent electrode. Moreover, a polarizing plate 35 is arranged onthe touch detection electrode TDL.

The liquid crystal layer 6 modulates light passing therethroughaccording to an electric field state, and uses a liquid crystal of anyof various modes such as a TN (Twisted Nematic) mode, a VA (VerticalAlignment) mode and a ECB (Electrically Controlled Birefringence) mode.

Although not illustrated herein, alignment films are arranged betweenthe liquid crystal layer 6 and the pixel substrate 2 and between theliquid crystal layer 6 and the opposed substrate 3, respectively, and anincident side polarizing plate is arranged on a lower surface of thepixel substrate 2.

FIG. 13 illustrates a configuration example of a pixel configuration inthe liquid crystal display device 20. The liquid crystal display device20 includes a plurality of pixels Pix arranged in a matrix form. Thepixels Pix each include a TFT element Tr and a liquid crystal elementLC. The TFT element Tr is configured of a thin film transistor, and inthis example, the TFT element Tr is configured of an re-channel MOS(Metal Oxide Semiconductor) type TFT. A source of the TFT element Tr isconnected to the pixel signal line SGL, and a gate thereof is connectedto the scanning signal line GCL, and a drain thereof is connected to anend of the liquid crystal element LC. The one end of the liquid crystalelement LC is connected to the drain of the TFT element Tr, and theother end thereof is connected to the drive electrode COML.

The pixels Pix assigned to the same row in the liquid crystal displaydevice 20 are connected to one another by the scanning signal line GCL.The scanning signal line GCL is connected to the gate driver 12, and thescanning signal Vscan (which will be described later) is supplied by thegate driver 12 to the scanning signal line GCL. Moreover, the pixels Pixassigned to the same column in the liquid crystal display device 20 areconnected to one another by the pixel signal line SGL. The pixel signalline SGL is connected to the source driver 13, and the pixel signal Vpix(which will be described later) is supplied from the source driver 13 tothe pixel signal line SGL.

Moreover, the pixels Pix assigned to the same row in the liquid crystaldisplay device 20 are connected to one another by the drive electrodesCOML. The drive electrodes COML are connected to the drive electrodedriver 14B, and the drive signal Vcom (the display drive signal Vcomdand the touch detection drive signal Vcomt) is supplied from the driveelectrode driver 14B to the drive electrodes COML.

The control section 17 is a circuit supplying control signals to thegate driver 12, the source driver 13, the drive electrode driver 14B andthe touch detection section 40 in response to a picture signal Vdispexternally supplied, respectively, to control them to operate insynchronization with one another.

The gate driver 12 has a function of sequentially selecting onehorizontal line to be subjected to a display drive of the display device10 with a touch detection function in response to the control signalsupplied from the control section 17. More specifically, the gate driver12 applies the scanning signal Vscan to the gates of the TFT elements Trof the pixels Pix through the scanning signal line GCL to sequentiallyselect pixels Pix to be subjected to a display drive configuring oneline (one horizontal line) from the pixels Pix formed in a matrix formin the liquid crystal display device 20 of the display device 10 with atouch detection function.

The source driver 13 is a circuit supplying the pixel signal Vpix toeach pixel Pix of the display device 10 with a touch detection functionin response to the control signal supplied from the control section 17.More specifically, as will be described later, the source driver 13supplies the pixel signal Vpix to the pixels Pix configuring onehorizontal line sequentially selected by the gate driver 12 through thepixel signal line SGL. Then, in these pixels Pix, one horizontal line isdisplayed in response to the supplied pixel signal Vpix.

The drive electrode driver 14B is a circuit supplying the drive signalVcom to the drive electrodes COML of the display device 10 with a touchdetection function in response to the control signal supplied from thecontrol section 17. More specifically, the drive electrode driver 14Bperforms display scanning by sequentially applying the display drivesignal Vcomd to the drive electrodes COML in a time-divisional manner ina display operation. Then, in a touch detection operation, as in thecase of the first embodiment, the touch detection drive signal Vcomt issequentially applied to the drive electrodes COML in a time-divisionalmanner to perform touch detection scanning.

In the touch detection operation, the display 7 with a touch detectionfunction operates as in the case of the touch detector 1 according tothe first embodiment. In other words, the drive electrode driver 14Bsimultaneously drives the drive electrodes COML corresponding to thetouch detection width b and performs scanning on the drive electrodesCOML with the scanning pitch a. The display device 10 with a touchdetection function outputs the touch detection signal Vdet based on thetouch detection drive signal Vcomt applied to the drive electrodes COMLin this drive. The touch detection section 40 detects the presence orabsence of a touch based on the touch detection signal Vdet to determinecoordinates or the like of a touched position when the presence of atouch is detected.

As described above, in the embodiment, the touch detection device andthe liquid crystal display device are integrated; therefore, the displaywith a touch detection function is allowed to be downsized. Othereffects are the same as those in the first embodiment.

In the above-described embodiment, the touch detection device 30according to the first embodiment and the liquid crystal display deviceare integrated; however, the technology is not limited thereto, and, forexample, the touch detection device 50 according to the secondembodiment and the liquid crystal display device may be integrated.

5. Application Examples

Next, referring to FIG. 14 to FIGS. 18A to 18G, application examples ofthe touch detector described in the above-described embodiments will bedescribed below. The touch detectors according to the above-describedembodiments and the like are applicable to electronic units in anyfields, such as televisions, digital cameras, notebook personalcomputers, portable terminal devices such as cellular phones, and videocameras. In other words, the touch detectors according to theabove-described embodiments and the like are applicable to electronicunits in any fields displaying a picture signal externally supplied or apicture signal produced inside as an image or a picture.

Application Example 1

FIG. 14 illustrates an appearance of a television to which the touchdetector according to any of the above-described embodiments and thelike is applied. The television includes, for example, a picture displayscreen section 510 including a front panel 511 and a filter glass 512,and the picture display screen section 510 is configured of the touchdetector according to any of the above-described embodiments and thelike.

Application Example 2

FIGS. 15A and 15B illustrate an appearance of a digital camera to whichthe touch detector according to any of the above-described embodimentsand the like is applied. The digital camera includes, for example, alight-emitting section for a flash 521, a display section 522, a menuswitch 523 and a shutter button 524, and the display section 522 isconfigured of the touch detector according to any of the above-describedembodiments and the like.

Application Example 3

FIG. 16 illustrates an appearance of a notebook personal computer towhich the touch detector according to any of the above-describedembodiments and the like is applied. The notebook personal computerincludes, for example, a main body 531, a keyboard 532 for operation ofinputting characters and the like and a display section 533 fordisplaying an image, and the display section 533 is configured of thetouch detector according to any of the above-described embodiments andthe like.

Application Example 4

FIG. 17 illustrates an appearance of a video camera to which the touchdetector according to any of the above-described embodiments and thelike is applied. The video camera includes, for example, a main body541, a lens for shooting an object 542 arranged on a front surface ofthe main body 541, a shooting start/stop switch 543 and a displaysection 544, and the display section 544 is configured of the touchdetector according to any of the above-described embodiments and thelike.

Application Example 5

FIGS. 18A to 18G illustrate an appearance of a cellular phone to whichthe touch detector according to any of the above-described embodimentsand the like is applied. The cellular phone is formed by connecting, forexample, a top-side enclosure 710 and a bottom-side enclosure 720 toeach other by a connection section (hinge section) 730, and the cellularphone includes a display 740, a sub-display 750, a picture light 760,and a camera 770. The display 740 or the sub-display 750 is configuredof the touch detector according to any of the above-describedembodiments and the like.

Although the present technology is described referring to theembodiments and application examples to electronic units; however, thetechnology is not limited thereto, and may be variously modified.

For example, in the third embodiment, the liquid crystal display device20 using a liquid crystal of any of various modes such as TN, VA and ECBand the touch detection device 30 are integrated to configure thedisplay device 10 with a touch detection function; however, a liquidcrystal display device using a transverse electric mode liquid crystalsuch as a FFS (Fringe Field Switching) mode or an IPS(In-Plane-Switching) mode and the touch detection device may beintegrated. For example, in the case where the transverse electric modeliquid crystal is used, a display device 60 with a touch detectionfunction is allowed to be configured as illustrated in FIG. 19. Thisdrawing illustrates an example of a sectional configuration of a mainpart of the display device 60 with a touch detection function, andillustrates a state where a liquid crystal layer 6B is sandwichedbetween a pixel substrate 2B and an opposed substrate 3B. Names,functions and the like of other components are the same as those in FIG.12, and will not be described. In this example, unlike the case of FIG.12, the drive electrode COML used for both of display and touchdetection is formed directly above the TFT substrate 21 to configure apart of the pixel substrate 2B. The pixel electrode 22 is arranged abovethe drive electrode COML with an insulating layer 23 in between. In thiscase, all dielectrics also including the liquid crystal layer 6B betweenthe drive electrodes COML and the touch detection electrodes TDLcontribute to the formation of the capacitive element C1.

The present application contains subject matter related to thatdisclosed in Japanese Priority Patent Application 2010-214188 filed inthe Japan Patent Office on Sep. 24, 2010, the entire content of which ishereby incorporated by reference.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A touch detector comprising: a plurality of driveelectrodes arranged side by side to extend in a first direction; adetection electrode extending in a second direction orthogonal to thefirst direction, and arranged to form a capacitance at each ofintersections with the drive electrodes; and a scanning drive sectionsequentially selecting a plurality of target electrodes from the driveelectrodes in a time-divisional manner, and applying a touch detectiondrive signal with a plurality of pulse waveforms for detecting anexternal object to the selected target electrodes to perform a scanningdrive, wherein a scanning pitch in the scanning drive and a total widthof the selected target electrodes are set independently of one another,such that: to increase a position resolution when a touched position isdetected, the total width of the selected target electrodes is fixed,and the scanning pitch is set to be smaller than the total width of theselected target electrodes, and to increase a detection sensitivity to atouch, the scanning pitch is fixed, and the total width of the selectedtarget electrodes is increased in a range in which the scanning pitch issmaller than the total width of the selected target electrodes, thescanning drive section sequentially selects the target electrodes byshifting the drive area by the scanning pitch so that the shifted drivearea includes a part of the most recently selected target electrodes,the drive electrodes include a predetermined number of kinds of driveelectrodes, the predetermined number of kinds of drive electrodes arealternatingly arranged side by side, and in the scanning drive, whilethe touch detection drive signal is simultaneously applied to one targetelectrode in addition to the predetermined number of target electrodesselected from the predetermined number of kinds of drive electrodeswhich are alternatingly arranged side by side, scanning is performed toshift the target electrodes by the predetermined number of targetelectrodes at a time.
 2. The touch detector according to claim 1,further comprising: a touch detection section sampling a detectionsignal of the detection electrode at timings according to transitions ofthe pulse waveforms of the touch detection drive signal to detect anexternal object.
 3. The touch detector according to claim 2, whereinwhen the scanning drive section drives the target electrodes, the touchdetection section completes detection of an external object in a regioncorresponding to the driven target electrodes.
 4. The touch detectoraccording to claim 3, wherein the selected target electrodes have anequal width.
 5. The touch detector according to claim 3, wherein thedrive electrodes include the predetermined number of kinds of driveelectrodes with different widths.
 6. The touch detector according toclaim 1, wherein the touch detection section determines the touchedposition based on all detection results obtained from the targetelectrodes sequentially selected.
 7. The touch detector according toclaim 1, further comprising a control section providing control signals,wherein the total width of the selected target electrodes and thescanning pitch are allowed to be independently controlled according tothe control signals provided by the control section.